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Two patients presented to the emergency department within three months with a laceration of the esophagus due to corn chip ingestion. Both complained of odynophagia, and each was evaluated for suspected perforation with confirming esophagrams. Both patients were treated nonoperatively with full recovery.
What to expect for hepatology in the 21st century? If science is allowed to proceed at its current rate, expectations can hardly be underestimated. Bound by the present day's limitations we are only able to see a glimpse of what could be available 100 years from now. For the next few decades, the global eradication of viral hepatitis will be on the agenda. For the treatment of inherited and acquired metabolic, toxic and immune liver disease, targeted drugs, genes and antisense oligonucleotides will be added to our therapeutic repertoire. The completion of the human genome project in 2003 will have far-reaching consequences: the widespread use of prenatal diagnosis, using DNA chip technology, may be expected to cause a dramatic decrease in the incidence of inherited diseases. Liver cirrhosis, hepatocellular carcinoma and inborn errors of metabolism may be treated by gene transfer or gene repair therapy. Although eventually these developments may decrease the need for organ transplantation, this by no means is the case yet and no solution is available for an increased demand and a decreased supply of organs. In the long run, diseases caused by multi-drug-resistant infectious agents and diseases associated with the abuse of alcohol and drugs are expected to become major problems. The future of university-based research is uncertain. The staggering costs of research and limited career possibilities may force universities to the limited task of higher education, with as a result biotech companies, shareholders and corporate finance ruling the scientific waves in the next century. The 21st century patient will know the way in cyberspace and will go shopping for the best doctor, for the best treatment and for the best, or friendliest, hospital.
Increasing evidence indicates a strong relationship exists between harmful habits like smoking and alcohol drinking and upper digestive tract cancer. In addition, smokers and alcohol drinkers also exhibit high salivary levels of carcinogenic acetaldehyde, the first metabolite of alcohol. This compound has been indicated as a major cancer causing factor in the upper digestive tract, especially among alcohol drinkers. Interestingly, acetaldehyde is produced from alcohol present in the epithelia by mucosal alcohol dehydrogenases (ADH) in the upper digestive tract. However, much higher levels derive from the bacterial oxidation of alcohol by the oral microflora. In this respect, the reduction of oral microbes can become a fundamental factor in diminishing the risk of cancer. In this article, we hypothesize that the antimicrobial agent chlorhexidine, formulated as controlled-release chip, and fixed by a dental device, (i.e., a modified orthodontic bracket), may be the most rational strategy for reducing acetaldehyde production by microflora.
High throughput transducers using metal cluster resonance technology are based on surface-enhancement of metal cluster light absorption. These devices can be used for detection of biorecognitive binding, as well as structural changes of nucleic acids, proteins or any other polymer. The optical property for the analytical application of metal cluster films is the so-called anomalous absorption. An absorbing film of clusters positioned 10--400 nm to a mirror surface reacts in a similar way to a reflection filter. At a certain distance of the absorbing layer to the mirror the reflected electromagnetic field has the same phase at the position of the absorbing cluster as the incident fields. This feedback mechanism strongly enhances the effective cluster absorption coefficient. The system is characterised by a narrow reflection minimum whose spectral position shifts sensitively with the interlayer thickness, because a given cluster-mirror distance and wavelength defines the optimum phase. Based on this principle a set of novel tools including biochips and micro arrays is presented, which enabled us to transduce binding, as well as changes of protein-, DNA- and polymer-conformation, quantitatively into an optical signal which can be observed directly as a colour change of a sensor-chip surface.
The "chip and flip" phacoemulsification technique increases safety and control within the capsular bag. The surgical maneuvers use a two-handed technique through a small curvilinear capsulorhexis.
A new planar bio-magnetic bead separator on a glass chip has been designed, fabricated and tested. The separator is composed of micromachined semi-encapsulated spiral electromagnets and fluid channels, which have been separately fabricated and then bonded. The device was tested with super-paramagnetic beads of mean diameter 1 microm which were suspended in a buffered solution. When a DC current of 300 mA was applied to the inductor, the bio-magnetic beads were successfully separated on the electromagnets, showing a functional capability as a magnetic bead separator. To evaluate separation rate and capability, the inductance measurement method has been introduced and the inductance variation according to the separation rate has been characterized. Using this separator, cells or cell fragments and magnetic beads bonded with protein or enzyme suspended in bio-buffer solutions can be successfully separated from their suspensions, envisaging a filterless bio-separator.
High density arrays of DNA fragments on a solid surface allow the expression of thousands of genes to be assessed in a single experiment. The development of this 'gene chip' technique heralds a new era of studies that promises to provide an integrated view of the expression of all genes of an organism.
Protein kinase chips, in which kinases are tested for their ability to phosphorylate immobilized substrates, have been developed and used to evaluate the protein kinases encoded by the yeast genome. This new technology promises to be a valuable addition to the biochemists' and cell biologists' arsenal for evaluating the substrate selectivity and function of protein kinases in cell signaling.
Microfluidics, or lab-on-a-chip technology, is proving to be a powerful, rapid, and efficient approach to a wide variety of bioanalytical and microscale biopreparative needs. The low materials consumption, combined with the potential for packing a large number of experiments in a few cubic centimeters, makes it an attractive technique for both initial screening and subsequent optimization of macromolecular crystallization conditions. Screening operations, which require a macromolecule solution with a standard set of premixed solutions, are relatively straightforward and have been successfully demonstrated in a microfluidics platform. Optimization methods, in which crystallization solutions are independently formulated from a range of stock solutions, are considerably more complex and have yet to be demonstrated. To be competitive with either approach, a microfluidics system must offer ease of operation, be able to maintain a sealed environment over several weeks to months, and give ready access for the observation and harvesting of crystals as they are grown.
It is expected that by the year 2003 the entire human genome will be sequenced, providing us with new insight into human disease. The amount of human sequence information that is already available (only a few percent of the total) is, however, already much greater than can be routinely evaluated with existing, commonly used diagnostic technology. New technology based on attaching DNA to a chip for parallel hybridization analysis is generating much interest in both the basic research and the clinical diagnostic community. It will increase, by orders of magnitude, our ability to evaluate an individual's genetic heritage and to conduct basic genetic research. The new technology will be a major advance in screening for genetic diseases, but the ability to treat these newly understood genetic defects will lag significantly behind the new-found diagnostic capabilities.
Microarray technology has become a crucial tool for large-scale and high-throughput biology. It allows fast, easy and parallel detection of thousands of addressable elements in a single experiment. In the past few years, protein microarray technology has shown its great potential in basic research, diagnostics and drug discovery. It has been applied to analyse antibody-antigen, protein-protein, protein-nucleic-acid, protein-lipid and protein-small-molecule interactions, as well as enzyme-substrate interactions. Recent progress in the field of protein chips includes surface chemistry, capture molecule attachment, protein labeling and detection methods, high-throughput protein/antibody production, and applications to analyse entire proteomes.
Oligonucleotide microarrays are amongst, a set of technologies that allow for high throughput assessment of vast numbers of gene expressions. In order to evaluate gene expressions given detection limits, antibody spiking is often used providing one with an expression curve relating antibody treated expression and non-antibody treated expression. These curves can exhibit different functional shapes across chips and hence need to be standardized. In addition, each curve is subject to saturation effects, which are typically dealt with by extrapolating a linear fit to the subset of the data not visually subject to saturation. In this paper we introduce methods for the non-parametric standardization of expression curves using univariate smoothers. We also explore parametric methods for more efficient analysis of the standardized curves. We demonstrate an alternate method of parametric analysis using a weighted linear mixed effects model that does not arbitrarily delete data beyond an observed saturation point; allows for natural grouping of genes and provides significantly more accurate predictions than naive linear extrapolation. Both methodologies are studied through sets of simulations.
One of the characteristics of the methylothrophic yeast Pichia pastoris is its ability to grow to a very high cell density. Biomass concentrations of 300-400 g wet mass/l are common. It is therefore obvious that the recovery processes of extracellular proteins from this microorganism should take into account the effect of high biomass content. Separation by filtration and/or centrifugation is possible but these steps are cumbersome and can affect the protein recovery. The use of fluidized beds is attractive proteins capture option since it eliminates the biomass while capturing the desired protein. Zirconia-based resins possess unique properties which make them appropriate for processing high biomass concentrations in an expanded bed mode. The beads are particularly heavy (density is 3.2 g/ml) and small (75 microm) and therefore can accommodate high fluidization velocity and high mass transport. Specific operating conditions for effective capture of expressed protein have to be determined. This determination is generally time consuming and requires relatively large amount of feedstock for the lab trials. To avoid multiple chromatographic trials in columns, optimal conditions of adsorption and elution were determined by ProteinChip technology coupled with mass spectrometry. This technology involves flat chip surfaces functionalized as chromatographic beads where it is possible to adsorb and desorb proteins. Four different functional groups (strong anion-exchange, weak cation-exchange, hydrophobic and metal chelate) were tested and the retained proteins were analyzed directly by mass spectrometry. The weak cation-exchange group was chosen for further work. The Zirconia-based weak cation-exchange sorbent (CM HyperZ) was evaluated for binding capacity in a packed column and then for capturing endostatin from crude feed stock. Based on the previously determined conditions; 45 l of culture containing approximately 15 kg of biomass (wet mass) and 3 g endostatin were applied on an expanded bed at a flow-rate of 535 cm/h, yielding 80% of the endostatin and removing approximately 80% of foreign proteins.
An outbreak of Salmonella paratyphi B infection in the UK associated with a fish-and-chip shop is reported. The source of infection for the first three cases was believed to be a food handler who was infected overseas 6 years earlier. His wife whose faeces and urine were originally culture negative continued to run the shop but subsequently her faeces became positive on one occasion. She was considered to have been the source of two further cases, and secondary household spread of infection from these two cases resulted in one symptomatic and two asymptomatic infections. A second household contact of the proprietor also became a faecal excretor 2 months later. We recommend that food handlers living in households or in intimate contact with cases or carriers of S. paratyphi B should be put off work until all household contacts cease excreting the organism.
Between April and September 1993, a nationwide outbreak of salmonellosis occurred in Germany which was traced to contaminated paprika and paprika-powdered potato chips. Of the estimated 1000 cases, children below 14 years were principally affected. Levels of 0.04-0.45 organisms per gram were found in the snacks. The infective dose was estimated at 4-45 organisms with an attack rate of 1 in 10,000 exposed persons. The unique feature of the outbreak was the variety of serovars involved. S. saintpaul, S. rubislaw and S. javiana were isolated during the same time period from paprika powder, spice mixtures, snacks and patients. Their clonal identity was confirmed by molecular typing methods. Furthermore, monophasic and non-motile strains of rare salmonella O-groups were isolated from both paprika products and patients. This is the largest documented outbreak due to contaminated spices which proved that even extremely low numbers of salmonellae adapted to the dry state were able to cause illness.
This report describes a new "lab-on-a-chip" protocol integrating on-line precolumn biocatalytic reactions of multiple (oxidase and dehydrogenase) enzymes and substrates with effective capillary electrophoresis microseparations and amperometric detection. The operation of the new oxidase/dehydrogenase reaction/separation microchip is illustrated for the simultaneous measurement of glucose and ethanol in connection to the corresponding glucose oxidase and alcohol dehydrogenase reactions, respectively. The enzymatic reactions generate hydrogen peroxide and NADH species that are separated (on the basis of their different charges) and detected amperometrically at the end-column thick-film detector. A driving voltage of 2000 V results in peroxide and NADH migration times of 74 and 230 s, respectively. Operating the gold-coated carbon detector at +1.0 V allows simultaneous anodic detection of both reaction products. Factors influencing the reaction, separation, and detection processes are examined and optimized. The applicability of the new multienzyme assay to wine samples is illustrated.
Monolithic porous polymers have been prepared by photoinitiated polymerization within the channels of a microfluidic device and used for on-chip solid-phase extraction and preconcentration. The preparation of the monolithic material with hydrophobic and ionizable surface chemistries is easily achieved by copolymerization of butyl methacrylate with ethylene dimethacrylate, or 2-hydroxyethyl methacrylate and [2-(methacryloyloxy)ethyl]trimethylammonium chloride with ethylene dimethacrylate, respectively. The porous properties, and consequently the flow resistance, of the monolithic device are controlled by the use of a mixture of hexane and methanol as a porogenic mixture. This mixture was designed to meet the specific requirements for pore formation within macroporous monoliths useful in the microfluidic formats. The low flow resistance enables high flow rates of up to 10 microL/min, which corresponds to a linear flow velocity of 50 mm/s and far exceeds the flow velocities typical of the common analytical microchips. The function of the monolithic concentration device was first demonstrated using very dilute solutions of Coumarin 519. The performance in a more realistic application was then demonstrated with the enrichment of a hydrophobic tetrapeptide and also of green fluorescent protein for which an increase in concentration by a factor as high as 10(3) was achieved.
The opacity and random surface orientation of process streams of solids complicates the application of spectroscopy to on-line analysis of solid streams. We have used a specialized form of thermal-emission mid-infrared spectroscopy, called transient infrared spectroscopy, combined with PLS regression to analyze a moving stream of wood chips for lignin, hemicellulose, glucan, and extractives content. Sixty-eight softwood samples from 6 species were analyzed using one regression, and 28 hardwood samples from 14 species were analyzed with another. Root-mean-square errors of prediction for the properties varied from 0.8 to 1.9 wt %, depending on property and wood type, with lignin and hemicellulose being the most accurately determined and glucan being the least.